Valve device for plastic extruder



Apriii 2,, 11968 D. H. CRISS VALVE DEVICE FOR PLASTIC EXTRUDER 2Sheets-Sheet 1 Filed March 11. 1966 V Fla-i 5@ r5 Z MW m fl J A N %2 avD. H. CRISS VALVE DEVICE FOR PLASTIC EXTRUDER April 2 3968 2Sheets-Sheet 2 Filed March 11, 1966 lnuenior. DONALD H. 62/55 PatentedApr. 2, 1968 3,375,553 VALVE DEVICE FOR PLASTIC EXTRUDER Donald H.Criss, Toledo, Ohio, assignor to Owens- Illinois, Inc., a corporation ofOhio Filed Mar. 11, 1966, Ser. No. 533,548 1 Claim. (Cl. 1830) Thisinvention relates to the plastic molding art, and more particularly toan apparatus for supplying plasticized material into a mold cavity whereit may be formed into an article.

In some plastic molding operations, it is necessary to sever a measuredamount of plasticized material from a parent mass, form the severedmaterial into a gob and deliver the gob to a specified place for furtherprocessing. Known apparatus for accomplishing these functions have notbeen entirely satisfactory. For example, if a measured amount ofmaterial is sheared off from the parent mass, the shearing action maydistort the severed gob or may leave scars in the material at thesevered end. If the gob is severed by pinching off a portion of themass, an irregular surface is left at the pinched region. Such scarsand/ or iregularities may result in fold lines, voids or other defectsin an article formed by compression, blowing or the like from the gob.Additionally, any such severing or pinching from a mass results inchilling a portion of the gob by its contact with the severing orpinching means.

The present invention proposes a novel apparatus for forming a gob ofplasticized material utilizing a novel valving, severing and displacingelement in combination with a separate and distinctmaterial-pressurizing means. This results in a clean, regular separationof the gob from the parent mass and also allows an end of the gob to beformed to a desired configuration. The separation is accomplishedwithout chilling the material by means of a control system which keepsthe valving and severing mechanism from being cooled unduly.

According to the invention, plasticized material is fed through an inletopening into a valve chamber having an outlet opening leading to a moldcavity. A movable valving member, which may be a rod, is then movedthrough the chamber past the inlet opening at least into the outletopening, so as to sever a gob of material from the material in the inletopening and push the gob completely out of the chamber and the outletopening into the mold cavity.

The amount of material fed into the cavity is determined entirelyseparately from the valving function, eg by means of a reciprocating androtational screw extruder which feeds material to the mold cavity viathe valve chamber. Only after the amount to be fed to the cavity hasbeen supplied to the valve does the valve deliver that amount to themold cavity.

The valve body in which the chamber and the movable valving member areprovided must remain substantially at the temperature of the plasticizedmaterial as it is supplied from the extruder. In this connection, afterthe movable member has completed a forward stroke to deliver material tothe mold cavity, the movable member is retracted to be inside the valvebody so that it will not cool below the temperature just referred to.Control circuitry is provided to accomplish this partial retraction ofthe movable member automatically.

Accordingly, it is an object of the invention to provide an improvedapparatus for severing a gob of plasticized material from a parent massof the material and delivering the gob to a mold cavity.

Another object of the invention is to provide an apparatus wherein a gobof plasticized material is separated from a parent mass by a movablemember which moves through a chamber past an inlet opening where thematerial is severed and into or through an outlet opening in which themember fits, thereby assuring that all material is expelled from thechamber and the outlet opening into the cavity.

Another object of the invention is to keep the movable member of thevalve device at the temperature at which the plasticized plasticmaterial is supplied to the valve device.

A further object of the invention is to incorporate in circuitry whichcontrols the movement of the movable member of the valve, control meansacting to retract the movable member to an intermediate position in thevalve body after it has delivered plasticized material into the moldcavity.

Other objects of this invention will appear in the following descriptionand appended claims, reference being had to the accompanying drawingsforming a part of this specification wherein like reference charactersdesignate corresponding parts in the several views.

On the drawings: I

FIGURE 1 is a sectional view of a valve device according to oneembodiment of the invention provided for an extruder and a mold cavity,the valve being shown in an open position;

FIGURE 2 shows the valve device of FIGURE 1 in a closed condition aftera gob of material has been severed and delivered by the valve device tothe mold cavity;

FIGURE 3 shows a plunger in the mold cavity inserted into materialsupplied to the cavity through the valve device of FIGURE 1;

FIGURE 4 shows the valve device of FIGURE 1 after .its movable memberhas been retracted into the body of the device; and

FIGURE 5 is a schematic diagram of a control circuit for controlling theextr'uder and the valve device.

Before explaining the present invention in detail, it is to beunderstood that the invention is not limited in its application to thedetails of construction and arrangement of parts illustrated in theaccompanying drawings, since the invention is capable of otherembodiments and of being practiced or carried out in various ways. Also,it is to be understood that the phraseology or terminology employedherein is for the purpose of description and not of limitation.

As shown on the drawings:

In FIGURE 1, there is a valve device 10 between an extruder 12 and amold cavity 14 for controlling the flow of plasticized material from theextruder to the mold cavity. The valve device 10 includes a block 16having an elongated chamber 18 therein in the form of a longitudinalbore. The bore or chamber 18 has an annular inlet opening 20 at the sidethereof and has an outlet opening 22 at one end thereof. The outletopening 22 leads from the chamber 18 into the mold cavity 14. The inletopening 20 leads from an annular passageway 24 into the chamber 18, thepassageway 24 in turn communicating with the barrel 26 of the extruder12.

There is a movable rod 28 in the elongated bore which forms the chamber18. This rod is movable from an open position (FIGURE 1) wherein it iswithdrawn from the outlet opening 22 to a point beyond the inlet opening20 to a closed position (FIGURE 2) where the rod has been moved past theinlet opening 20 into the outlet opening 22. It is evident that when therod 28 is in its open position, both the inlet opening and outletopening of chamber 18 are open. Conversely, when the rod is in itsclosed position as in FIGURE 2, it closes both the outlet opening andthe inlet opening to the chamber 18.

One end of the rod 28 extends into a cylinder 30 in which there is apiston 32 connected to the rod 28. The piston may be actuated downwardas viewed in FIGURE 1 to push rod 28 through the chamber 18 to itsclosed position. The piston 32 may subsequently be actuated in thereverse direction to pull rod 28 away from opening 22 to a mid-positionas shown in FIGURE 4. This partial retraction of rod 28 serves to keepthe rod at the temperature of the incoming plasticized material, sincethe rod is withdrawn into the mass of the valve body 16 and is not leftexposed at the outlet opening. The partial retraction stroke is causedby the control circuit as will be explained later herein. The controlcircuit ultimately causes the rod 28 to be fully withdrawn to theposition shown in FIGURE 1.

The extruder 12 is of the reciprocating and rotational type. It includesa screw 34 provided in barrel 26 and attached at one end to a gear 36which is driven by a pinion 38 connected to a motor 40. A shaft 42 isafifixed at one end to the gear 36 and is also affixed to a piston 44provided in a cylinder 46. The piston 44 may be actuated to the right tomove screw 34 axially to the right as viewed in FIGURE 1 to therebyforce a charge of material from the extruder through passageway 24 intothe chamber 18 of the valve device.

Granular plastic material is fed to the extruder 12 through a hopper 48which communicates at its lower end with the interior of the barrel 26.This material is advanced through the barrel by the rotating screw 34and becomes plasticized before it reaches the end 50 of the barrel. Whena charge of plasticized material has accumulated in the barrel 26, thescrew 34 may be pushed to the right by actuation of piston 44 aspreviously explained in order to fill the valve chamber 18 withplasticized material. The other piston 32 is then actuated to push rod28 through chamber 18 into the outlet opening 22 to thereby sever a gobof plasticized material from the material in the inlet opening 20 of thevalve device and deliver this gob of material to the cavity 14 .insidethe mold 15.

'In FIGURE 2, a gob 70 of plasticized material has been expelled fromthe chamber 18 of the valve device 10, and the gob 70 has fallen freelyto the bottom of cavity 14 inside mold 15. The valve device is shown inits closed condition, and the gob 70 is shown in a cylindrical formbefore it has a chance to conform to the shape of the mold cavity 14.The plunger 54 is outside of the mold at this stage of the processing,but it will be evident that the valve device 10 may be removed from thetop of the mold and the plunger 54 may then be moved into alignment withthe cavity 14 and inserted in the cavity as shown in FIGURE 3 so as toform a parison 71 by compression molding the gob 70. A finish portion 73of the parison is formed in the neck mold 56. Although the mold is shownas a parison mold in which a subsequently blown shape is formed, it isunderstood that other finished or intermediate articles can be made bythe techniques of this invention.

A typical sequence of operation will be described beginning withactuation of piston 44 to move the extruder screw 34 to the right asviewed in FIGURE 1. First, a manually actuated or machine actuatedswitch MS1 (FIGURE 5) is closed -to complete an energizing circuit for arelay CR1. The latter relay pulls in and its contacts CR1-1 close tohold it in. Contacts CR1-2 close to energize solenoid S1 which operatesa valve V1 associated with cylinder 46. Valve V1 moves to the right toconnect passage 90 with fluid source 92 such that fluid flows from thesource into cylinder 46 pushing piston 44 to the right, therebysupplying plasticized material into and through chamber 18. In theillustrated embodiment, the amount of material fed to chamber 18 andnecessary to form the desired article or parison is more than enough tofill the chamber 18, and the excess material projects down throughoutlet opening 22 as shown at 23.

Contacts CR1-3 also close to energize another solenoid S3 for a valveV2, and this causes movable member 28 of valve device 10 to move fromits intermediate position (FIGURE 4) to its open position (FIGURE 1).This function of solenoid S3 will be described more fully later herein.

When piston 44 has moved fully to the right to the position shown inFIGURE 1, as required to issue the desired amount of material to andthrough the chamber 18, a collar 43 on shaft 42 actuates a limit switchLS1 which in turn actuates a relay CR2 (FIGURE 5). Contacts CR2-1 of thelatter relay open dropping out relay CR1 which in turn opens itscontacts CR1-2 and CR1-3 to deenergize the solenoids S1 and S3. Valve V1then shifts to the left due to the bias of spring SP1 to connect passage91 to drain 93 so that fluid can flow out of chamber 46 on the returnstroke of piston 44.

Meanwhile, contacts CR2-2 close to hold in relay CR2 1 and contacts CR23close to energize another solenoid S2 for a valve V2 associated wtihcylinder 30 and piston 32. The solenoid S2 moves valve V2 to the left tothereby connect fluid source 94 to inlet 96 on the upper side of piston30. Fluid fromsource 94 can then flow into cylinder 30 above piston 32to push the piston and movable member 28 downward as viewed in FIGURE 1.As movable member 28 moves through chamber 18, it pushes the material 70(FIGURE 2) into the mold cavity 14 and continues moving downward untilits forward end 29 is in the outlet opening 22 in the position shown inFIG- URE 2.

At this stage, a collar 98 on member 28 actuates a limit switch LS2which energizes a relay CR3 (FIGURE 5). Contacts CR3-1 of the latterrelay are in circuit-with relay CR2, and these normally closed contactsopen to deenergize relay CR2,thus opening contacts CR2-3 to deenergizesolenoid S2. The valve V2 is then urged by cen tering springs SP2 andSP3 back to its centered position where it is ready for actuation tostart a return stroke. Contacts CR32 of relayCR3 close to hold in thisrelay and contacts CR3-3 close to energize solenoid S3 for valve V2.This solenoid moves valve V2 to the right to connect fluid source 94 tothe inlet 100 of the chamber 30 which is below the piston 32. As fluidflows into this space, piston 32 is forced upward, thus beginning thereturn stroke of movable member 28.

When the end 29 of member 28 has reached the intermediate position shownin FIGURE 4, the return stroke of piston 32 is halted temporarily toallow the screw extruder 12 to accumulate a fresh charge. The screw 34,gear 36 and shaft 42 all move axially to the left as the chargeaccumulates at the right end of the barrel 26. During this time, the end29 of movable member 28 is not exposed to a cooling environment sinceitis withdrawn into the body of the valve device 10. It is desired tokeep all parts of the valve device 10 which contact plasticizedvmaterialup to the temperature of the material as it leaves the .extruder, andthe partial withdrawing of the movable member 28 helps to accomplishthis while keeping the valve device 10 closed to I allow a fresh chargeof material to accumulate.

The halting of the return stroke of member 28 happens when the collar 98actuates limit switch LS3. Relay CR4 then pulls in opening its normallyclosed contacts CR4-1 to drop out relay CR-3.;Contacts CR3-3 thenopen todeenergize solenoid S3, and valve V2 returns to its neutral position dueto the opposing bias of springs SP2 and SP3.

As shaft 42 of extruder 12 moves to the left, it will ultimately actuatea normally closed limt switch LS4. The opening of limit switch LS4deenergizes the motor 40 which rotates the extruder screw 34, so theextruder stops at this stage with the member 28 still in itsintermediate position. At the beginning of the next cycle, switch MS1 isclosed to again energize relay CR1, and as previously mentioned,contacts CR1-3 of this relay close to energize solenoid S3. Valve V2 isagain pushed to the right to connect fluid source 94 to inlet 100 ofchamber 30, thus driving piston 32 upward again. When piston 32 reachesits fully retracted position as shown in FIGURE 1, the collar 98actuates a normally closed limit switch LS5 to in turn deenergizesolenoid S3. This stops the retraction stroke of piston 32 and rod 28.

By comparing FIGURES 1 and 2 it is evident that the rod 28 acts as apiston which moves through the chamber 18 at least into the outletopening 22 so as to completely expel all plasticized material whichinitially is in the chamber out of the chamber and into the cavity 14.The gob of material so expelled is severed around its circumference fromthe material in the inlet opening 20. After the rod 28 reaches itsclosed position as in FIGURE 2, there is no material remaining in thechamber 18 nor in the outlet opening 22. The cut-off end of the gob isformed by the face 29 of the rod such that the gob of material does notbecome distorted as it is pushed through the chamber nor are anydistorting scars left by the severing action of the rod. The rod may bepushed all the way through the outlet opening into the cavity 14 ifdesired, but this is not necessary to the invention. Chilling of the rodis prevented by withdrawing it to the intermediate position within valvebody 15, and this helps to keep all parts of the valve device up to thetemperature of the plasticized material after it leaves the extruder.The valve device does not measure nor determine the amount of materialthat is fed to the cavity; that function is accomplished entirelyseparately as by an extruder such that the valve device only delivers tothe cavity whatever amount of material is supplied to it.

I claim:

1. In molding apparatus including a mold having a cavity therein and anextruder screw of the rotational and reciprocatory type, a valve deviceand control means for separating a gob of plasticized material from aparent mass of material supplied from the extruder comprising meansforming a chamber having an outlet opening leading therefrom into saidmold cavity and an inlet opening leading from said extruder into saidchamber, a movable member having (1) a valve-closed position in saidoutlet opening in which said movable member blocks said inlet openingand is exposed at an end thereof to the ambient temperature in said moldcavity which tends to lower the temperature of said end, (2) avalve-open position away from both of said openings providing an openpassage for flow of plasticized material from said extruder into saidchamber, and (3) an intermediate position between said valve-open andvalve-closed positions wherein said movable member blocks said passageand said end thereof is Withdrawn from said mold cavity and is at thetemperature of plasticized material as it is supplied to said inletopening, first actuator means for moving said extruder screw axially tosupply a charge of plasticized material to said chamber with saidmovable member in said valve-open position, said first actuator meansincluding a first piston and cylinder device for moving said extruderscrew axially, a first valve controlling said piston and cylinder deviceand a first solenoid controlling said valve, second actuator meansoperative to move said movable member from said valve-open position tosaid valve-closed position to sever a gob of plasticized material fromplasticized material in said inlet opening and to force said gob intosaid cavity, and third actuator means operable to retract said movablemember from said valve-closed position to said intermediate position andhalt said movable member at said intermediate position, said thirdactuator means acting in response to actuation of said extruder screw bysaid first actuator means to deliver a charge of material to saidchamber to further retract said movable member from said intermediateposition to said valve-open position providing an open passage forfeeding said material to said chamber, said second and third actuatormeans together including a second piston and cylinder device for movingsaid movable member reciprocally, a second valve controlling said secondpiston and cylinder device, a second solenoid for actuating said secondvalve in one sense to cause movement of said movable member from saidvalve-open position toward said valve-closed position, a third solenoidfor actuating said second valve in an opposite sense to cause movementof said movable member from said valve-closed position to said valveopenposition, and switching means operative with said third solenoid to haltsaid movable member temporarily in said intermediate position.

References Cited UNITED STATES PATENTS 3,231,656 1/1966 Ninneman 264-3293,196,198 7/1965 Rex 264-329 3,025,567 3/1962 Sherman 264-328 2,834,1545/1958 Koob 264-97 2,890,491 6/1959 Hendry 264-329 2,505,540 4/ 1950Goldhard 18-30 2,944,288 7/1960 Sherman 264-329 FOREIGN PATENTS 10,0768/1962 Japan.

10,077 8/1962 Japan.

80,070 1/1963 France.

ROBERT F. WHITE, Primary Examiner. R. B. MOFFITI, A. R. NOE, AssistantExaminers.

1. IN MOLDING APPARATUS INCLUDING A MOLD HAVING A CAVITY THEREIN AND ANEXTRUDER SCREW OF THE ROTATIONAL AND RECIPOROCATORY TYPE, A VALVE DEVICEAND CONTROL MEANS FOR SEPARATING A GOB OF PLASTICIZED MATERIAL FROM APARENT MASS OF MATERIAL SUPPLIED FROM THE EXTRUDER COMPRISING MEANSFORMING A CHAMBER HAVING AN OUTLET OPENING LEADING THEREFROM INTO SAIDMOLD CAVITY AND AN INLET OPENING LEADING FROM SAID EXTRUDER INTO SAIDCHAMBER, A MOVABLE MEMBER HAVING (1) A VALVE-CLOSED POSITION IN SAIDOUTLET OPENING IN WHICH SAID MOVABLE MEMBER BLOCKS SAID INLET OPENINGAND IS EXPOSED AT AN END THEREOF TO THE AMBIENT TEMPERATURE IN SAID MOLDCAVITY WHICH TENDS TO LOWER THE TEMPERATURE OF SAID END, (2) AVALVE-OPEN POSITION AWAY FROM BOTH OF SAID OPENINGS PROVIDING AN OPENPASSAGE FOR FLOW OF PLASTICIZED MATERIAL FROM SAID EXTRUDER INTO SAIDCHAMBER, AND (3) AN INTERMEDIATE POSITION BETWEEN SAID VALVE-OPEN ANDVALVE-CLOSED POSITIONS WHEREIN SAID MOVABLE MEMBER BLOCKS SAID PASSAGEAND SAID END THEREOF IS WITHDRAWN FROM SAID MOLD CAVITY AND IS AT THETEMPERATURE OF PLASTICIZED MATERIAL AS IT IS SUPPLIED TO SAID INLETOPENING, FIRST ACTUATOR MEANS FOR MOVING SAID EXTRUDER SCREW AXIALLY TOSUPPLY A CHARGE OF PLASTICIZED MATERIAL TO SAID CHAMBER WITH SAIDMOVABLE MEMBER IN SAID VALVE-OPEN POSITION, SAID FIRST ACTUATOR MEANSINCLUDING A FIRST PISTON AND CYLINDER DEVICE FOR MOVING SAID EXTRUDERSCREW AXIALLY, A FIRST VALVE CONTROLLING SAID VALVE, SECOND ACTUATORMEANS OPERATIVE TO MOVE SAID MOVABLE MEMBER FROM SAID VALVE-OPENPOSITION TO SAID VALVE-CLOSED POSITION TO SEVER A GOB OF PLASTICIZEDMATERIAL FROM PLASTICIZED MATERIAL IN SAID INLET OPENING AND TO FORCESAID GOB INTO SAID CAVITY, AND THIRD ACTUATOR MEANS OPERABLE TO RETRACTSAID MOVABLE MEMBER FROM SAID VALVE-CLOSED POSITION TO SAID INTERMEDIATEPOSITION AND HALT SAID MOVABLE MEMBER AT SAID INTERMEDIATE POSITION,SAID THIRD ACTUATOR MEANS ACTING IN RESPONSE TO ACTUATION OF SAIDEXTRUDER SCREW BY SAID FIRST ACTUATOR MEANS TO DELIVER A CHARGE OFMATERIAL TO SAID CHAMBER TO FURTHER RETRACT SAID MOVABLE MEMBER FROMSAID INTERMEDIATE POSITION TO SAID VALVE-EMBER FROM PROVIDING AN OPENPASSAGE FOR FEEDING SAID MATERIAL TO SAID CHAMBER, SAID SECOND AND THIRDACTUATOR MEANS TGETHER INCLUDING A SECOND PISTON AND CYLINDER DEVICE FORMOVING SAID MOVABLE MEMBER RECIPROCALLY, A SECOND VALVE CONTROLLING SAIDSECOND PISTON AND CYLINDER DEVICE, A SECOND SOLENOID FOR ACTUATING SAIDSECOND VALVE IN ONE SENSE TO CAUSE MOVEMENT OF SAID MOVABLE MEMBER FROMSAID VALVE-OPEN POSITION TOWARD SAID VALVE-CLOSED POSITION, A THIRDSOLENOID FOR ACTUATING SAID SECOND VALVE IN AN OPPOSITE SENSE TO CAUSEMOVEMENT OF SAID MOVABLE MEMBER FROM SAID VALVE-CLOSED POSITION TO SAIDVALVEOPEN POSITION, AND SWITCHING MEANS OPERATIVE WITH SAID THIRDSOLENOID TO HALT SAID MOVABLE MEMBER TEMPORARO IN SAID INTERMEDIATEPOSITION.